CHARACTERIZATION OF SUPERCONDUCTING HG-BA-CA-CU-OXIDES - STRUCTURAL AND PHYSICAL ASPECTS

Some of the recently discovered high-T(c) superconducting phases of Hg-Ba-Ca-Cu-oxides have been investigated and characterised by analytical and high-resolution transmission electron microscopy. The highest measured critical temperature T(c) of 133.5 K can be assigned to the Hg1Ba2Ca2Cu3O8+x phase (Hg-1223). Besides Hg-1212 and Hg-1223 phases, different perfectly-ordered polytypes with large c-axes up to 19 nm consisting of different stackings of Hg-1212 and Hg-1223 have been observed. The investigated oxide materials contain also several different stacking defects consisting of intercalated layers of the related Hg-1234 and Hg-1245 structures.